1. Field of the Invention
The present invention relates to a wired circuit board and a producing method thereof. More particularly, the present invention relates to a wired circuit board, such as a suspension board with circuit, and a producing method thereof.
2. Description of the Related Art
A hard disk drive is equipped with a suspension board with circuit on which a magnetic head is mounted. In a typical suspension board with circuit, an insulating layer made of a resin and a conductive pattern made of copper are formed in this order on a metal supporting board made of stainless steel.
In such a suspension board with circuit, since a metal supporting board is formed of stainless steel, a transmission loss in a conductive pattern is increased.
To reduce the transmission loss, it is proposed that an insulating layer is formed on a suspension made of stainless steel, a lower conductor made of copper or a copper alloy is formed on the insulating layer, and an insulating layer, a conductor of record-side and reproduction-side are formed in this order on the lower conductor (see, e.g., Japanese Unexamined Patent No. 2005-11387).
A suspension board with circuit is also proposed which includes a metal supporting board, a metal thin film formed on the metal supporting board, a metal foil formed on the metal thin film, an insulating layer formed on the metal foil, and a conductive pattern formed on the insulating layer (see, e.g., Japanese Unexamined Patent No. 2006-245220).